Field of the Invention
The present invention relates to an apparatus and method for cutting a sheet for use in an image forming apparatus capable of obtaining cut sheet products by supplying a continuous sheet.
Description of the Related Art
In known image forming apparatuses capable of obtaining cut sheet products from a continuous sheet, a plurality of processes are performed including image formation and cutting from sheet supply to completion. The sheet is subjected to various processes while being conveyed, in which the sheet conveying speed are changed from one process to another.
In particular, in conventional upstream and downstream processes including a cutting process, it is necessary to change the conveying speed or to stop the conveyance depending on the situation due to differences in processing speed required in halting the sheet for cutting and in the upstream and downstream processes.
A photo-printing apparatus disclosed in Japanese Patent Laid-Open No. 1-99049 is provided in view of the problem that, in the flow of printing a sheet, cutting the sheet, and conveying the sheet to a developing process, the conveying speed is low and constant, while at the printing process, the conveying speed is high and intermittent. Japanese Patent Laid-Open No. 1-99049 discloses a method for coping with the difference in conveying speed by providing a conveying-speed adjusting unit capable of controlling the nip and separation of the sheet behind the cutting unit, instead of a conventional loop-like storage portion.
In this type of image forming apparatus, the need for enhancing the performance, such as increasing the speed and reducing the size, is always present as an object, also the need for apparatus specifications, such as controlling the conveying speed by easily coping with mixture of products of different lengths as a requirement.